Process and apparatus for the production of double-walled tubes



June 8 1926. S 1,587,933

F. BARME PROCESS AND APPARATUS FOR THE PRODUCTION OF DOUBLE WALLBD TUBESFiled Sept. 15, 1924 Patented June 8, 1926.

PATIENT OFFICE.

FRIEDRICH BARME, OF ELBERFELD, GERMANY.

PROCESS ANJJAPPARATUS FOR THE PBODI TCTION OF DOUBLE-WALLED TUBES.

Application filed September 15, 1924, Serial No. 737,948, and in GermanyAugust 27', 1923.

The invention relates to the pressing of double-walled tubes from leador like suitable material, of the kind in which the inner tube isconnected to the outer tube by conand driven through the hollow shapingspace of the press mould Without interruption.

According to this invention the working material isfed to thehollowshaping spaces of the press mould from the outside inwardly. Incontradistinction to the reverse process, the working material is inthis way led together at all points for, the purpose of uniting it, itspath being at the same time shortened. By this method the finishedcomplete tube is improved because there can be no seams in the outertube and the working material for the inner tube is securely closedtogether. At the same time also the press mould can be made simpler thanfor the reverse process.

a is an upright container, in which isthe plastic material (for instancemolten lead) which can be pressed upwards out of the container by anysuitable, for instance,hydraulic press apparatus, not shown. The

a ,press mould is situated in the head of this 40 container. The outerpart consists of a press ring 71 seatedin a cover m of the container a.The inner part consists of a hollow member 0? with a cylindrical punch72.

situated therein. The hollow member cl is secured by a' plug 0 into asocket b mountedin the container a. The hollow member 4 has longitudinalslots so that the upper part of the hollow mem er d consists of fourtongues d, between which are the slots 7'.

In this way the press mould has hollow spaces at its outlet mouth whichcorrespond to the material cross section of the doublewalled tube(Figure 1) to be pressed.

I f the pressing apparatus is put into operation, then the lasticworking material (for instance lead is forced from outside into thevarious hollow spaces of the press mould. In the direction of the arrow1 it passes inwards through the slots 7 and between the .tongues 03 andthe punch h-to form the inner tube Z; in the direction of the arrow 2 itpasses between the pressing ring 13 and the tongues dlto form the outertube 2, and in the direction of the arrow 3 it rises upwards in theslots f to form the connecting strips 3. The double-walled tube isextended from the press mould, its length corresponding to the quantityof the material which is fed as desired into the container a.

As mentioned above, not only lead but other metals, or even othernon-metallic plastic materials such as rubber, for instance, can also bepressed.

What I claim is .41. A press mold embodying a container, a hollow membertherein having separated passa es and radial slots.

2. A press mold embodying a container, a hollow member therein havingseparated passages and radial slots, and annular tongues between thesaid slots.

3. The method herein described of making double-walled tubes fromplastic material, consisting in feeding plastic material toward an axisand organizing the same into two concentric streams, forcing thesestreams through two circular concentric dies to form inner and outerpipes, permitting the streams -to work radially toward one another atspaced points to provide connecting webs between the inner and outerpipes, and leaving the spaces between the pipes and intermediate saidwebs unobstructed to form passa'geways for the circulation of fluid.

In testimony whereof I hereunto aflix my signature.

" FRIEDRICH BARME.

